1. Field of the Invention
The present invention relates to a photomagnetic differential reproducing system for recording and reproducing information data to and from a recording medium of a ferromagnetic substance at a high S/N ratio.
2. Description of the Prior Art
Recently, there has been an increasingly strong demand for systems which can record and reproduce a large quantity of information with the advance of the information-related industry. Therefore, photomagnetic recording/reproducing systems are highlighted owing to their capability of recording and reproducing information data in high density.
An example of these photomagnetic recording/reproducing systems is disclosed in Japan Published Unexamined Patent Application No. 58-196640. In this system, however, it is difficult to improve the S/N ratio. This is because in the photomagnetic method a change in the polarizing angle of the reproduced light is extremely small in response to a change in magnetization direction.
To overcome the above-mentioned drawbacks, some photomagnetic reproducing systems of differential type have been proposed. In these prior art systems, however, since a half mirror having a reflection factor of 50% for both p-polarized light and s-polarized light is incorporated therewithin, there still exists problems in that it is extremely difficult to manufacture the half mirror (R.sub.p =R.sub.s =50%). Additionally, the mirror easily absorbs the produced light and causes a phase difference between reflected and transmitted light, so that the voltage levels of two signals obtained by transducing the reflected and transmitted lights are reduced together with noise included therein, thus raising a problem such that the S/N ratio is not satisfactorily high.
The arrangement and configuration of a prior art photomagnetic differential reproducing system will be described in further detail hereinafter with reference to the attached drawings under the DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS.